Moveable interiors?

#1 Difs can be moved, but that isn't recomended as the shadows won't match anymore. It would be better to make your ship a dts object and assign the movement to it. Shadows will move with the ship.

#2 I highly doubt shadows matter that much for a giant ocean-going ship, and without the polysoup features of T3D, a DTS's collision will likely be too limited to represent a full game map.

Anyway, here's a resource link you might find useful -- the OP has dropped support for it, and the downloads links in the process, but if you follow the chains on the forums you should be able to find a mirror. I believe it was intended to move DTS objects with the Player riding on them, but it could be altered to include DIF files.

www.torquepowered.com/community/blogs/view/12188

If you just try to move your DIF interiors without linking the Player to them, you'll quickly see that they simply slide out from under the Player, so if you don't go for a resource like this, you'll still have to apply movement of the ship to the players on board anyway.

#3 Or, question whether it's really necessary to move the entire ship - you could make the ship stationary, and move the rest of the level around it. Since that's only really likely to be water it should be much less troublesome ;).